1. Field of the Invention
This invention relates to an air intake apparatus of a motorcycle.
2. Description of Background Art
In some motorcycles, air cleaned by an air cleaner is fed into carburetors of respective cylinders of the engine of the motorcycle. In each carburetor, air is mixed with evaporated fuel to form an air-fuel mixture. The air-fuel mixture is then fed into each cylinder of the engine. In such an engine, pulsations occur in the intake passage due to the intermittent intake stroke of each cylinder. These pulsations are transmitted to an air cleaner provided upstream of the intake passage and cause intake noise.
To prevent such intake noise in some motorcycles, a sub-chamber is provided midway along the intake passage between the air cleaner and the carburetor to reduce the transmission of the pulsations, and the intake noise is reduced. For example, FIGS. 5(A) and 5(B) show a motorcycle including a V-type engine 100 having a front cylinder 100a and a rear cylinder 100b. A sub-chamber 103 is provided midway along the air intake passage between an air cleaner 101 and a pair of carburetors 102a, 102b. The sub-chamber 103 is disposed above the front cylinder. The sub-chamber 103 is connected to the carburetors 102a, 102b through a pair of communication tubes 104a, 104b.
Alternately, in some motorcycles, an air intake chamber is provided on the upstream side of an air cleaner for reducing air intake pulsations (refer to Japanese Patent Laid-open No. Hei 8-108877). In that arrangement, the air intake chamber is disposed above a V-type engine and extends over the main frame.
A sub-chamber or air intake chamber having a large volume is desirable for suppressing the transmission of air intake pulsations, but it is difficult to obtain the desired volume when the sub-chamber is disposed at the above-mentioned location.